1. Field Of The Invention
The present invention relates to a ratchet wrench having two modes of operation and which is characterized by a small head and simplicity of construction and operation. One mode is the conventional mode whereby the bar is swung back and forth to progress the socket holding means; the other mode shall be called "speed ratcheting" and is achieved by ratcheting the handle along its longitudinal axis. This is made possible by the coordination of a coupling gear and a tandem ratcheting mechanism between the socket holding member and the grip.
2. General Background
Considerable attention has been placed on the development of ratchet wrenches with smaller heads, which wrenches are thus capable of being used in close quarters. The limiting factor in reducing the size of the ratchet head in conventional ratchets has been the strength of the teeth and the pawls. State of the art conventional ratchet wrenches have smaller heads than older models even though the ratcheting mechanisms continue to be incorporated in the lead. This is made possible by the use of alloys with greater strength and proper positioning of the pawls.
Several patents have been granted for ratcheting devices which have the conventional mode of ratcheting facility combined with another mode made possible by gear action between the work engaging piece and a rotatable handle. This action enables the user to tighten or loosen a nut or bolt by rotation of the handle along the longitudinal axis. The introduction of these devices demonstrates that conventional ratchet trenches even with smaller heads do not meet all the requirements in working on modern congested engines. There is a need for the dual mode type ratchet wrench. However, these devices characteristically have very large heads and numerous working parts. The heads are much larger than the heads of conventional ratchets because both the ratchet mechanism and the mitre gears must be housed in the same area. In short, these tools are not practical to manufacture and/or operate.
U.S. Pat. No. 3,952,617 disclosed a ratchet wrench having two modes of operation as thus described. In this design the ratcheting mechanisms are in the handle making it possible to reduce the size of the head considerably. The limiting factor in reducing the size of the head in this tool is the strength of the mitre gears and the shaft. In conventional ratcheting the torque from the work engaging member must be transmitted through the gears and shaft to the ratchets in the handle. This tool went further than any prior ratchet wrench in achieving the dual mode of operation and featuring a small head. However, the numerous and complex parts make it expensive to manufacture. Also, the rotation of the handle along its center longitudinal axis is limited to rotation in one direction in a given setting as the torque in conventional ratcheting is transmitted from one pawl through the rotatable handle to the second pawl. The user must remove his or her grasp from the handle after each stroke and re-grip. The handle cannot be ratcheted along its center longitudinal axis.